The isolation and examination of P. falciparum mutants will be continued. The long term goals are developing attenuated parasite strains with conditionally lethal, temperature sensitive mutant characters or other types of mutants that affect critical processes involved in parasite growth, parasite-host interactions or contribute to parasite pathogenicity. Testing of temperature sensitive mutants will be done to examine their ability to induce a protective immunity in Aotus trivergatus trivergatus monkeys while producing a benign infection. Mutants will be characterized, to analyze the cellular processes or properties that contribute to the mutant phenotype. Cloning of the P. falciparum genetic material coding for the parasite enzymes dihydrofolate reductase and ornithine decarboxylase will be eventually be done. The development of a system for the in vitro genetic transformation of P. falciparum will be pursued to facilitate further studies of the parasite.